Mumetal, magnetic shielding work in clean roomMumetal plate installation. Magnetic shielding work in clean roomMagnetic shielding for lithography / mask writer room

Several photo mask production rooms had to be magnetically shielded with mu-metal to protect the lithography mask writers from EMI. The rooms meet cleanroom specifications according to ISO Class 3, which specifies e.g. no more than 35 particles larger than 0.5 µm (0.5 micro-meters) per m2.

While building mu-metal, permalloy, shielded rooms is challanging anyway, designing and building mu-metal shielded room inside a clean room environment is a task itself. To meet clean room class 3 specifications, material must not only be clean, but must be of clean room compatible material, too.

 
 

Magnetically shielded room for lithography. Shielding integrates mask feeder.Magnetically shielded tool with integrated feederFeeder integrated shielding design

In this special mask writer application, the tool itself is completely housed inside the shielded room, sitting on a concrete foundation. However, the feeders remain accessible from outside of the shielded room, maintaining completely unimpeded access. This special "feeder integrated" shielding design was developped by Systron and is used for applications with very high requirements regarding attenuation of the shielding, cleanlyness of the room and servicability of the tool.
 
During production, the tool room is never accessed and remains locked. The room is accessed only, if service is necessary. With the feeder integrated design, masks can be loaded from outside and are then automatically pulled into the vacuum chamber inside the shielded room. Even so magnetically shielded rooms in clean rooms are a big challange, Systron is able to provide not only proven, but also economical solutions.
Room in room shielding systemRoom in room shielding system, free standing frame
Installation of magnetic shielding panels inside the tool room.Installation of shielding panels inside the tool room.
Mu-metal magnetically shielded room in semiconductor fabrication Mu-metal magnetically shielded room in semiconductor fabrication Magnetic field measurements in shielded clean roomMagnetic field measurements in magnetically shielded clean room